Technical Field
The present disclosure generally relates to electromagnetic navigation, and more particularly, to systems, methods, and computer-readable media for calibrating and optimizing an electromagnetic navigation system.
Discussion of Related Art
Electromagnetic navigation (EMN) has helped expand medical imaging, diagnosis, prognosis, and treatment capabilities by enabling a location and/or an orientation of a medical device to be accurately determined while the device is within the body of a patient. One example of a medical procedure in which EMN is employed is ELECTROMAGNETIC NAVIGATION BRONCHOSCOPY® (ENB™), which includes a planning phase and a navigation phase. During the planning phase, a computed tomography (CT) scan of the chest of the patient is used to generate a virtual three-dimensional bronchial map of the patient and a planned pathway for the navigation phase. During the navigation phase, a field generating antenna assembly radiates an electromagnetic signal (for example, including one or more cosine waves) throughout a sensing volume within which the chest of the patient is positioned. A practitioner inserts into the airway of the patient an electromagnetic sensor that senses the radiated electromagnetic signal. A computing device captures a sample of the electromagnetic signal during a sampling window, and determines a location and/or an orientation (e.g., relative to the planned pathway) of the electromagnetic sensor based on characteristics (e.g., amplitude and/or phase) of the sampled electromagnetic signal and based on a previously generated mapping of electromagnetic signal measurements at respective sensor locations in the sensing volume.
In some cases—for instance, because of various sensor or antenna inductances, signal chain delays (e.g., analog or digital), and/or any delay from when the synchronization pulse occurs to when the acquisition or electromagnetic field generation actually begins—the sampled electromagnetic signal captured during the sampling window may not include a perfect cosine (or sine) waveform. Also, because of variations in the output current level(s) of transmitter channel(s) and/or in the gain(s) of receiver channel circuitry, the amplitude of the sampled electromagnetic signal captured at a particular location and orientation within the sensing volume relative to the field generating antenna assembly may vary from system to system. Additionally, because generating the mapping of electromagnetic signal measurements at respective sensor locations in the sensing volume can be laborious and time consuming, it may be desirable to reuse in multiple other systems a mapping that was previously generated based on an initial system. In order to do so, however, the initial system and the multiple other systems may require calibration to some common baseline.
Given the foregoing, a need exists for systems and methods for calibrating and/or optimizing an electromagnetic navigation system.